Randomness Thing

Hello, science believer! Welcome to another edition of Nature’s Wonder and this time, we will still be discussing about our neighbour, the moon.

Previously, you guys have witnessed how the moon shapes like the present form today with the help of Lunar Reconaissance Orbiter from NASA. This time I will explain why Earth has one moon just like today.

There are four theories that condensed around how the moon is created:

The Fission Theory: This theory proposes that the Moon was once part of the Earth and somehow separated from the Earth early in the history of the solar system. The present Pacific Ocean basin is the most popular site for the part of the Earth from which the Moon came. This theory was thought possible since the Moon’s composition resembles that of the Earth’s mantle and a rapidly spinning Earth could have cast off the Moon from its outer layers. However, the present-day Earth-Moon system should contain “fossil evidence” of this rapid spin and it does not. Also, this hypothesis does not have a natural explanation for the extra baking the lunar material has received.

The Capture Theory: This theory proposes that the Moon was formed somewhere else in the solar system, and was later captured by the gravitational field of the Earth. The Moon’s different chemical composition could be explained if it formed elsewhere in the solar system, however, capture into the Moon’s present orbit is very improbable. Something would have to slow it down by just the right amount at just the right time, and scientists are reluctant to believe in such “fine tuning”. Also, this hypothesis does not have a natural explanation for the extra baking the lunar material has received.

The Condensation Theory: This theory proposes that the Moon and the Earth condensed individually from the nebula that formed the solar system, with the Moon formed in orbit around the Earth. However, if the Moon formed in the vicinity of the Earth it should have nearly the same composition. Specifically, it should possess a significant iron core, and it does not. Also, this hypothesis does not have a natural explanation for the extra baking the lunar material has received.

There is one theory which remains to be discussed, and it is widely accepted today.

The Giant Impactor Theory (sometimes called The Ejected Ring Theory): This theory proposes that a planetesimal (or small planet) the size of Mars struck the Earth just after the formation of the solar system, ejecting large volumes of heated material from the outer layers of both objects. A disk of orbiting material was formed, and this matter eventually stuck together to form the Moon in orbit around the Earth. This theory can explain why the Moon is made mostly of rock and how the rock was excessively heated. Furthermore, we see evidence in many places in the solar system that such collisions were common late in the formative stages of the solar system.